The techniques of spraying paint by airless spray devices is well known. These devices are called airless because no air or gas is mixed with the paint during spraying. The fluid is forced under sufficient pressure to pass through an aperture in a nozzle which causes atomization of the fluid, the density and velocity of the fluid passing through the nozzle being conventionally regulated by using a needle valve extending into the aperture of the nozzle.
Airless spraying devices have several advantages over other forms of spray painting, such as the paint dries faster than air mixed techniques because no air is mixed in the paint. Further, since a minimum number of moving parts are used inside the airless spray devices, the possibility of sparks are inhibited, thus, airless spraying is recommended for inside chemical plants. Further, an airless spray gun provides a more aimable and directional spray than other spray guns, which permits the spraying of more paint in less time and inhibits the necessity of additional coats of paint. The major problem with airless spraying devices has been the use of high pressures, upwards of 1500 psi, to force the paint through the gun. These high pressures can frequently cause penetration of paint through the skin of careless painters and damage surfaces being painted. Moreover, these high pressures require a continuously operating compressor and heavily reinforced structures to handle these high pressures. Thus, the devices are quite expensive because of the amount of equipment and construction of equipment. Further, these prior art airless spray devices are not portable because heavy hoses extend from the compressor to the paint source and from the paint source to the spray gun. This requires a painter to fix a position from which to paint around and then drag heavy hoses after him while painting.
Accordingly, it is an object of the present invention to provide a portable airless spraying device which permits movement to relatively inaccessible locations for spraying.
Further, it is an object of the present invention to provide a portable airless spraying device that is designed to be inexpensive and portable by eliminating some of the structure used in prior art airless spraying devices.
Further, it is an object of the present invention to provide a portable spray device that uses low gas pressures and does not mix the gas with the paint during spraying.
Further, it is an object of the invention to provide a portable airless spray device that uses a limited number of moving parts.
Further, it is an object of the present invention to provide a portable airless spray device that is aimable and directional in applying paint.
In accordance with the invention, a portable airless spraying device using an airless spray gun for spraying paint and a hose mounted with such spray gun for carrying paint to the gun is disclosed. The device includes a vessel having a dividing wall to provide a first compartment within the vessel for holding a quantity of paint and a second compartment within the vessel for holding pressurized gas. A gas inlet apparatus is mounted with the second compartment of the vessel for receiving gas from a gas supply mechanism and a paint inlet apparatus is mounted with the first compartment of the vessel for receiving paint. A coupling mechanism is mounted with the first compartment to mount the hose to the vessel and a pick-up tube is mounted within the first compartment of the vessel with an inlet in close proximity to the bottom of the first compartment and an outlet mounted with the coupling mechanism. Conduit apparatus is mounted with the vessel and leads from the first compartment to the second compartment to carry pressurized gas from the second compartment to the first compartment for pushing the paint from the first compartment through the pick-up tube and hose to the airless spray gun.